This invention relates to a two-terminal semiconductor device of surface installation type such as a semiconductor diode, and more particularly to the structure of the lead terminals thereof.
In one example of a conventional two-terminal semiconductor device of surface installation type, a semiconductor chip is mounted on a lead frame and hermetically packaged with resin as shown in FIGS. 10 and 11. In these figures, reference numeral 1 designates a semiconductor chip; 2, a resin package which hermetically seals the semiconductor chip 1; 3, lead strips extended from the package 2; and 4, an auxiliary lead strip.
A method of manufacturing the semiconductor device thus constructed will be described with reference to FIGS. 11(a)-11(d). As shown in FIG. 11(a), the semiconductor chip 1 is mounted on a predetermined portion of a lead frame 5 which is formed by pressing a metal plate into a desired shape, and the auxiliary lead strip 4 is soldered to the semiconductor chip 1 and another lead frame 5. Thereafter, as shown FIG. 11(b), the semiconductor chip 1 is packaged by transfer molding; that is, the resin package 2 is formed. Under this condition, the lead frames 5 are cut along one-dot chain lines, to form a semiconductor device as shown in FIG. 11(c). Then, as shown in FIG. 11(d), the lead strips 3 extended from both end faces of the package 2 are subjected to forming work, more specifically, they are bent downwardly and then inwardly in such a manner that the outer end portions of the lead strips 3 are flush with each other, so that they are deformed into a hairpin shape.
The semiconductor device thus formed is installed on a printed circuit board as follows: The semiconductor device is mounted on the printed circuit board through the outer end portions of the lead strips 3, and the latter are secured to the printed circuit board by reflow soldering for instance.
The above-described conventional two-terminal semiconductor device of surface installation type, when manufactured and handled, suffers from the following difficulties:
(1) The semiconductor chips 1 are mounted on the lead frames 5 which are designed only for the semiconductor device. Therefore, the cost of manufacturing the lead frames including the metal mold is considerably high.
(2) In order to connect the semiconductor chip to the lead strip 3 of the lead frame 5, it is necessary to use the auxiliary lead strip 4 and to solder it.
(3) During manufacturing, the semiconductor devices are integrally coupled to one another through the side rails and the tie bars of the lead frames, and therefore they cannot be tested until the lead frames are cut as was described above.